Potential use of the SWOT satellite to characterize the hydrodynamic of the estuaries and coasts

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1 WOT Potential use of the SWOT satellite to characterize the hydrodynamic of the estuaries and coasts Laignel B. 1, Turki I. 1, Chevalier L. 1, Salameh E. 1,2, Soloy A. 1, Lyard F. 2, Frappart F. 2, Desroches D. 3, Cherchali S. 3, Escudier P. 3 1: Normandie University, UNIROUEN, UNICAEN, CNRS, M2C, Rouen, France, +33(0) , benoit.laignel@univ-rouen.fr 2: UMR 5566 LEGOS, Observatoire Midi-Pyrénées, 14 Avenue Edouard Belin, Toulouse 3: CNES, 18 Avenue Edouard Belin, Toulouse TOSCA-CNES program N o r m a n d i e

2 WOT Coastal zones (including estuaries & deltas) The coastal zones = environments with geomorphological, sedimentary, hydrodynamic & biological contexts very diverse & complex estuaries, deltas, bays, shelfs, rocky coasts with cliffs, beaches with sand (with dunes or not), gravel, pebbles or mud, & the wetlands (mangroves, coastal marshes, swamps ) = Among the most affected by human impact (High urbanization & strong harbour, industrial & tourism activities) = Among the most affected by climate change (sea level rise, storm surges & river floods)

3 WOT Complex hydrodynamics and satellites measurements Spatialized monitoring of hydrodynamics = essential for a good managment of the coastal environments, but it is difficult: - Complex hydrodynamic in connection with many hydro-meteo-marine phenomena (offshore currents, waves, tides, storm surges, sea level rise (climate change), streamflow) - Effects of the phenomena and their interactions are different according to very diverse morphology, sedimentary & climate contexts - Tide gauges are sparsed and located in sheltered areas (such as harbours) Remote sensing observations can provide critical information on the spatial variability of water surface elevations But radar altimeters encounter many problems in the coastal environments: - rapid degradation of the data accuracy when approaching the coast - nadir altimeter missions have an inter-track spacing which limits their ability to map smaller-scale features in the coastal zone SWOT SAR-interferometric altimeter: higher spatial resolution & excellent global coverage resolve the problems of the conventional altimeters & fundamental data: to map the spatial variability of water surface elevations under different hydrodynamic conditions & at different scales (local, regional and global) to improve our knowledge of the complexity of the physical processes & their interactions in the coastal & estuarine systems

SWOT : Surface Water and Ocean Topography = New generation of Altimeter very innovative Swot produces: Heights & co-registered all-weather imagery SWOT Originality Ka-band SAR interferometric

4 SWOT : Surface Water and Ocean Topography = New generation of Altimeter very innovative Swot produces: Heights & co-registered all-weather imagery SWOT Originality Ka-band SAR interferometric innovative system with 2 swaths Width observed on the ground: 140 km Complete coverage of the globe in one cycle of days Spatial resolution: Ocean 1 km River width: 100 m (50 m) Lake 250m x 250 m (100x100m) Vertical accuracy of water level: Ocean ~1 to 3 cm Continental water ~ <10 to 18 cm Cycle of days with 1-7 passages according to the location 1 day orbit during 3 months for some sites Launch in 2021

Objective and Approaches To study the ability of SWOT to reproduce the spatial and temporal variability of the hydrodynamic in the coastal and estuarine environments Two approaches applied on 16

5 Objective and Approaches To study the ability of SWOT to reproduce the spatial and temporal variability of the hydrodynamic in the coastal and estuarine environments Two approaches applied on 16 study sites 16 study sites Selected in different tide contexts (macro, meso & microtidal), diverse morphologies (estuary, delta, bay, coast with sandy beaches or cliffs, shelf), different climates (temperate, mediterranean, tropical, arctic ) - Comparison of in situ and simulated SWOT data from statistical and signal processing methods = Study of the SWOT ability to reproduce the hydrodynamic temporal variability - Combining of hydrodynamic modeling (T-UGO, DELFT-3D models) and SWOT simulator HR & LR (High and Low Resolution) = Study of the SWOT ability to reproduce the hydrodynamic spatial variability

6 Simulation of the temporal SWOT data Débits Lat Long SWOT Passage (in hours) Seine 49, , , , ,9861 Exemple SWOT orbite : 891 Days 4, , , Simulate SWOT data without error & with white noise (erreur hauteur) : From the SWOT orbit! We sample the time series of water level or discharge during 5 years according to the passage frequency of SWOT! Comparison of the temporal hydrological variability in situ and simulated SWOT data from several analyses (trend, loess, wavelet analysis )! Impact of SWOT revisit on its ability to restitute the temporal hydro. variability

Temp. hydrodynamic reproduction by SWOT in the estuaries =hydro cycle =high & low water =flood period SWOT Upstream Estuary -

Downstream Estuary tide & river context (Aliasing in macrotidal context, Turki et al.

4 "Rita Ike In Situ - Good reproduction in upstream estuary = similar to the river Hydro cycle, seasonal variability, flood period

7 Temp. hydrodynamic reproduction by SWOT in the estuaries =hydro cycle =high & low water =flood period SWOT Upstream Estuary - Reproduction more Morphodynamique heterogeneous Continentale & difficult et Côtièrein downstream estuary Difference according to the Downstream Estuary tide & river context (Aliasing in macrotidal context, Turki et al., 2015) Aliasing - Possibility to observe the energy of some hurricanes & storms in microtidal context 1y =Hurricane cat.4 "Rita Ike In Situ - Good reproduction in upstream estuary = similar to the river Hydro cycle, seasonal variability, flood period Mississippi Delta 1y Ike SWOT In Situ Microtidal Macrotidal - Best reproduction by SWOT in microtidal (73-90) than macrotidal context (50-87) - Decrease of the coherence from upstream (87-90) to downstream(50-82) = tide influence

SWOT SWOT ability to reproduce the temporal variation of the sea level in the coastal

=Tempête Storm surge " Nemo SWOT Wavelet Coherence Atlantic-Connecticut bay Gulf of

coastal zones of Mississippi & Connecticut than the Channel: according to tide context

8 SWOT SWOT ability to reproduce the temporal variation of the sea level in the coastal zones & aliasing phenomenon In situ The Channel Macrotidal =Marée Equinoxe 2-3 m =Tempête Storm surge " Nemo SWOT Wavelet Coherence Atlantic-Connecticut bay Gulf of Mexico-Mississippi coast Microtidal Microtidal 53 à 65% 73% 82% Best reproduction in the coastal zones of Mississippi & Connecticut than the Channel: according to tide context Exaggeration of the variability mode 2-4m = Aliasing between SWOT revisit and some components of the tide

9 WOT Comparison of the SWOT potentiality with the other satellites Wavelet coherence between in situ and satellites signals on 6 sites (Bays and Estuaries) Best coherence between in situ and satellites signals : SWOT 1 & 21 days Soloy et al., Submitted

10 Modeling - SWOT HR and LR simulator Accurate modeling of the spatial & temporal variability of water level T-UGOm, DELFT-3D, TELEMAC! Coupling of the model data (as input data) & the SWOT HR & LR simulator In different hydrodynamic conditions Coastline: Neap tide/spring tide,high/low tide, with or without storm surges Estuary : Neap tide/spring tide,high/low tide, high/medium/low discharge! SWOT ability to reproduce the spatial hydrological variability in different hydrodynamic conditions

Hydrodynamic modeling in the estuary and coast T-UGOm in the Seine estuary DELFT-3D in The Channel High discharge Medium discharge Low discharge Spring tide Low tide High tide 1 2 5 6 9 10 Turki et

11 Hydrodynamic modeling in the estuary and coast T-UGOm in the Seine estuary DELFT-3D in The Channel High discharge Medium discharge Low discharge Spring tide Low tide High tide Turki et al., 2015 Low tide Neap tide High tide The hydrodynamic modeling in the estuaries and coasts : Water levels are spatially highly variable in different hydrodynamic conditions & in specific hydro. condition Resolutions of 100 m in estuaries & 250 m in coastline, bay & shelf seems the best compromise between the spatial resolution & vertical precision to observe the major physical processes Importance of the high spatial resolution of SWOT to observe these transitions & better understand & model these spatial variations

restitution of the spatial variability of the water level along the estuary from the downstream to upstream (length: 160 km) Ex 1 (high variability):

12 Coupling of modeling/swot HR simulator in the seine estuary Case 1 Variation of -4 to 4,5 from downstream to upstream -4m 4m/5m Chevalier et al., Soumis Case 8 Variation of 1 m by section Variation of 1-2m by section All of SWOT measurement points are in the channel HR simulator shows a good restitution of the spatial variability of the water level along the estuary from the downstream to upstream (length: 160 km) Ex 1 (high variability): simulator reproduces well the 8 m of difference of water level from upstream to downstream Ex 8 (low variability): simulator reproduces well the 1 meter of difference of water level by section

13 WOT Conclusion The SWOT satellite (Surface Water and Ocean Topography; NASA and CNES mission; launch in 2021) is a new generation of altimeter very innovative SWOT will offer new opportunities to survey the hydrodynamic in the coastal environments because it will provide data on the water level with an high spatial resolution (oceans: 1 km, rivers: 100 m of width) and with a global cover The results of our study in 16 coastal and estuarine sites show: - a best reproduction by SWOT in microtidal (wavelet coherence: 73-90) than macrotidal contexts (50-87) - a decrease of the reproduction from upstream (87-90) to downstream estuary and coast (50-82) - an aliasing problem mainly in macrotidal context - the observation of some hurricanes, storms & floods - a good restitution of the spatial variability of the water level along the estuary in 12 different hydrodynamic conditions (high/low tide, neap/spring tide, highmedium-low discharge) by the combining of modeling and SWOT simulator HR

14 WOT

Coastal ocean studies in the SWOT Science Team

Coastal ocean studies in the SWOT Science Team Pierre De Mey 1, Benoit Laignel 2, Rosemary Morrow 1, Han Guoqi 3, Nadia Ayoub 1, Marc Simard 4 1 LEGOS, France; 2 M2C, France; 3 Fisheries and Oceans, Canada;